Striped metallic nanowires are interesting building blocks for the assembly of more complex structures with emergent properties and functions. We have recently demonstrated the acoustic propulsion and magnetic steering of nanowire motors.1,2Here we report that segmented gold-ruthenium-nickel nanorods (300 � 30 nm in diameter and 2.0� 0.2 �m in length) assemble into few particle, geometrically regular dimers, trimers and higher multimers. The assembly is controlled by interactions between the ferromagnetic Ni stripes at one end of the nanorods. These nanorod multimers can be propelled autonomously in fluids by using ~4 MHz ultrasound and exhibit several distinct modes of motion. Multimer assembly and disassembly are dynamic in the ultrasonic field. The relative numbers of monomers, dimers, trimers, and higher multimers are dependent upon the number density of particles in the fluid and the speed of the motors, which is determined by the ultrasonic power applied. The autonomously propelled multimers are also steerable with an external magnetic field and are robust, remaining intact after removal from the acoustic chamber for SEM imaging.(1) Wang, W.; Castro, L. A.; Hoyos, M.; Mallouk, T. E. ACS nano 2012  , 6, 6122�32.(2) Ahmed, S.; Wang, W.; Mair, L. O.; Fraleigh, R. D.; Li, S.; Castro, L. A.; Hoyos, M.; Huang, T. J.; Mallouk, T. E. Langmuir?: the ACS journal of surfaces and colloids 2013  , 29, 16113�8.

Dynamic self-assembly of nanowire motors into regular geometric multimers

248th National Meeting (2014)

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